This invention relates to a high fidelity loudspeaker system and, in particular, to an improved vented enclosure system.
In order to obtain substantial low frequency sound from a high fidelity loudspeaker, a baffle must be used with the speaker. This is normally accomplished by mounting the speaker in a wall of an enclosure, that is, a box or cabinet. In some designs the enclosure is sealed; in others, there is a vent opening in the enclosure. Some of the enclosures are vented through a duct; these are variously called ducted port, tuned port or tube vented systems.
Most loudspeaker enclosures have an internal volume of a few cubic feet or less. At such a size, air enclosed in the box represents a significant load on the moving element of the low frequency driver, ordinarily a dynamic loudspeaker with a moving cone. This load has considerable effect on the net motion of the speaker cone. The load takes various forms, according to the particular enclosure design employed, but one effect common to the several conventional designs is that produced by air turbulence. The effect of the moving speaker cone is to produce a motion of the air inside the enclosure that is characterized by a significant amount of turbulence. The turbulence of the air introduces a random component into the motion of the loudspeaker cone, giving rise to distortions in the sound produced by the system. The loudspeaker system of the present invention represents a solution to the distortion problem created by this turbulence.